The present invention relates to a magnetic tape cartridge suitable for high-density recording.
In recent years, means for high-speed information transmission such as optical fibers have attained considerable development, which makes it possible to transmit images and data sets containing enormous quantity of information, while at the same time, advanced technologies to record, reproduce and store these data sets are being required. Typical recording and reproducing media include flexible discs, magnetic drums, hard discs and magnetic tapes, and the magnetic tapes play a major role mainly as data backup medium since their recording capacity per reel is large. Today, with increase in the level of technology, the magnetic tapes are required to have higher recording capacity.
The magnetic tapes are applied to various uses such as audio tapes, video tapes and computer tapes. In the field of data backup tapes in particular, with increased capacity of hard discs which are targets of backup operation, magnetic tapes having a recording capacity of over 200 GB per reel have been produced on a commercial basis. In the future, mass-storage backup tapes with a capacity of over 1 TB are expected to be introduced to market, and therefore it is vital to develop magnetic tapes with high recording capacity.
The data backup magnetic tape is usually wound onto reels and used in the state of being housed in cartridge. The magnetic tape cartridges fall into two categories: a single reel type which houses one reel; and a double reel type which houses two reels.
FIG. 13 is an outer perspective view showing a single reel-type magnetic tape cartridge. In FIG. 13, a cartridge 21 is composed of a top shell 22 and a bottom shell 23. FIG. 14 is a fragmentary cross sectional view taken along line I-I in FIG. 14. In FIG. 13, a magnetic tape 24 is wound onto a reel 25 having an upper flange 29a and a lower flange 29b. The reel 25, which is housed in between the top shell 22 and the bottom shell 23, is pressed toward the bottom shell 23 by a reel spring 26. As shown in FIG. 14, the magnetic tape 24 is stored in the state of being wound onto the reel 25. FIG. 15 is a plane view showing the cartridge 21 in FIG. 13 without the top shell 22. In FIG. 15, the reel 25 having the upper flange 29a and having the magnetic tape 24 wound therearound is mounted on the bottom shell 23. Moreover, in FIG. 15, a leader pin 27 for winding off the tape is attached to the fore end of the magnetic tape 24. FIG. 16 is a fragmentary cross sectional view showing a position of the reel 25 when the magnetic tape 24 is loaded. In FIG. 16, the reel 25 is lifted by a drive gear 28 and the magnetic tape 24 is positioned in the middle of the top shell 22 and the bottom shell 23.
As means to increase the recording capacity of the magnetic tape cartridges, a method for achieving high recording density of the magnetic tapes themselves, and a method for decreasing the thickness of the magnetic tapes to be housed so as to enlarge recording areas have been proposed (see, e.g., JP H10-222837 A and JP 2004-133997 A1). While these methods can enhance the recording capacity of the magnetic tape cartridges, they are still not enough to satisfy the demands.
Accordingly, a method for achieving high recording capacity by increasing the length of the magnetic tapes, and a method for achieving high recording capacity by increasing the width of the magnetic tapes are being studied. However, in each of these methods, the size of existing cartridges needs to be changed, which causes a problem that compatibility with conventional recording and reproducing devices cannot be secured. More particularly, the method for increasing the length of the magnetic tapes enlarges the winding diameter of the magnetic tapes, which makes it necessary to increase the size of the cartridges in the direction of the winding diameter. Further, the method for increasing the width of the magnetic tapes requires the thickness of the cartridges to be increased.
These problems are herein described in detail. The magnetic tape cartridges record and reproduce data in the state of being loaded onto recording and reproducing devices. As mass storage recording and reproducing devices, library-type recording and reproducing devices capable of loading a plurality of cartridges are used. The library-type recording and reproducing devices include those housing a plurality of cartridges in a magazine and loading a plurality of the magazines to record and reproduce data, and those having a plurality of cartridge housing slots on the inner wall of the recording and reproducing device and housing the cartridges in the housing slots to record and reproduce data.
FIG. 17 is an outer perspective view showing one example of the magazines for use in the library-type recording and reproducing devices. In FIG. 17, a magazine 30 has a cartridge housing space 32 formed by a plurality of partitions 31. Since cartridges vary in thickness, an interval H of the partitions 31 is set in conformity with the maximum thickness of existing cartridges. Also in the library-type recording and reproducing devices having cartridge housing slots, the size of housing space is set in conformity with the maximum size of existing cartridges. Consequently, changing the thickness or the size of cartridges beyond a certain limit means losing compatibility with the existing recording and reproducing devices.